Unit:
Κατεύθυνση Ηλεκτρονική και Ραδιοηλεκτρολογία (Ρ/Η, με πρόσθετη εξειδίκευση στις Τηλεπικοινωνίες και στην επεξεργασία και διοίκηση της Πληροφορίας)Library of the School of Science
Supervisors info:
Έκτορας Νισταζάκης, Αναπληρωτής Καθηγητής, τμήμα Φυσικής, ΕΚΠΑ
Συσκάκης Εμμανουήλ, Επίκουρος Καθηγητής, τμήμα Φυσικής, ΕΚΠΑ
Ευγενία Ροδίτη, Επίκουρη Καθηγήτρια, τμήμα Φυσικής, ΕΚΠΑ
Άννα Τζανακάκη, Επίκουρη Καθηγήτρια, τμήμα Φυσικής, ΕΚΠΑ
Original Title:
Λεπτά υμένια διοξειδίου του βαναδίου V02 ως οπτικά φίλτρα στην περιοχή των Ασύρματων Οπτικών Επικοινωνιών: Θεωρητική και Πειραματική Διερεύνηση
Translated title:
VO2 thin films as optical filters in the area of Wireless Visual Communications: Theoretical and Experimental Investigation
Summary:
Visible Light Communications (VLC) systems have attracted research and commercial interest over the last few years due to the remarkable characteristics such as the high data rate, low installation and operational cost and the fact that they are environmentally friendly. The transmitter in such systems can be a LED that offers advantageous properties such as brightness, extremely high data transmission and long lifetime, whereas photodiodes are employed as receivers. Therefore, VLC is already used for applications of 5G technology communication networks. However indoor VLC’s performance is decreased due to the background noise which is mainly caused by the sunlight radiation. In order to reduce the noise of sunlight, in this work is studied the application of a vanadium dioxide (VO2) optical filter in front of the receiver for the improvement of a VLC system’s Signal-to-Noise Ratio (SNR). The Metal-Insulator-Transition (MIT) of the Vanadium dioxide (VO2) at a temperature of 340 K is accompanied by a large change in its electrical resistance and optical transmittance combined with its very rapid phase shift structure. The Vanadium dioxide - VO2 optical transmittance appears to decrease after the metal insulator transition to a range of visible and infrared wavelengths with a maximum transmittance of 650-700nm giving the possibility of using vanadium dioxide VO2 as an optical filter.
In particular, thin vanadium pentoxide (V2O5) films were prepared by the Physical Vapor Deposition (PVD) method, where they were reduced to thin films (VO2).The samples were characterized by X-ray diffractometry measurements and their electrical resistance was measured in terms of both temperature and optical transmittance in terms of wavelength and temperature. Then, the performance, improvement SNR of the system (VLC) was studied after applying the experimental results of an optical vanadium dioxide (VO2) filter in front of the receiver to reduce sunlight noise. The obtained results are illustrated through suitable three dimensional figures.
Main subject category:
Science
Other subject categories:
Physics
Solid state physics
Electronics
Keywords:
VO2, thin films, VLC, ΜΙΤ, PVD, SNR, optical filter
